Evaporation system and process



P. GEIRINGER 3,489,654

EVAPORATION SYSTEM AND PROCESS Jan. 13, 1970 Filed Jan. 9, 1967 3 Sheets-Sheet l 25 26 27 Jet Compressor 32 l3 l2 I4 34 I 33 24 4 2.9 3/ 3 Heater 28 52 Salt Water Feed 66 Heuel' l/ 54 Flash Dgs hllahon System 59 Steam Condensate Feed Water Tank Fi i.

g INVENTOR.

Paul L. Geiringer mama ATTORNEYS Jan. 13, 1970 P. L. GEIRING'ER 3,489,654

EVAPORATION SYSTEM AND PROCESS Filed Jan. 9, 1967 3 Sheets-Sheet 2 //03 25 26 Jet Compressor Heurer Turbine Steam Condensate I0 I07 I09 Feed Water Tank F lg. 2.

IN VENTOR.

ATTORNEYS Jan. 13, 1970 P. L. GEIRINGER 3,489,65

EVAPORATION SYSTEM AND PROCESS Filed Jan. 9, 1967 3 Sheets-Sheet 5 Jet Compressor Heufer 29 Feed Water Tank INVENTOR. Paul L. Geiringer ATTORNEYS United States Patent 3,489,654 EVAPORATION SYSTEM AND PROCESS Paul L. Gein'nger, Eastchester, N.Y., assignor to American Hydrotherm Corporation Continuation-impart of application Ser. No. 355,963, Mar. 30, 1964. This application Jan. 9, 1967, Ser. No.

Int. Cl. B01b 3/06, 3/00 US. Cl. 203-26 8 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of application Ser. No. 355,963, filed Mar. 30, 1964, now abandoned.

This invention relates to an improved system and method for effecting the evaporation of a liquid and more particularly relates to the evaporation of water.

The use of vapor compression for effecting the evaporation of liquids is known in the art and in general, such systems employ a power driven rotating or reciprocating compressor. These compressors require considerable investment, operating and maintenance expenses. In addition, during compression, the steam becomes superheated and consequently requires de-superheating before being reused.

An object of this invention is to provide a new and improved system and method for evaporating a liquid.

Another object of this invention is to provide a system and method for evaporating a liquid that has improved efficiency.

A further object of this invention is to provide a system and method for evaporating a liquid that effects vapor compression with simpler and less costly equipment.

Still another object of this invention is to provide a method and system for evaporating a liquid that reduces operating costs.

A still further object of this invention is to provide a system and method that is particularly adapted to the evaporation of brine, brackish water, waste water and the like.

These and other objects should be readily apparent from the following detailed description of the invention when read with reference to the accompanying drawings where- FIGURE 1 is a simplified schematic flow diagram of an embodiment of the invention;

FIGURE 2 is a simplified schematic flow diagram of another embodiment of the invention; and

FIGURE 3 is a simplified schematic flow diagram of a further embodiment of the invention.

The objects of this invention are broadly accomplished by providing an evaporation system which utilizes a stationary jet compression system for reenergizing low pressure vapor withdrawn from an evaporation system. The excess vapor generated by the use of the jet compressor is utilized for other purposes, such as in a turbine to generate power or as a source of heat for a multi-stage evaporation system.

More particularly, steam withdrawn from one of the lower pressure effects of a multi-effect vapor compression evaporation system, is drawn into a jet compressor by 3,489,654 Patented Jan. 13, 1970 a motive fluid, such as high temperature, high pressure steam or water, preferably water, wherein the pressure of the steam is raised to a higher pressure. The steam at a higher pressure is then introduced into a higher pressure effect of the multi-effect vapor compression ivaporation system to supply the heat requirements there- In accordance with one embodiment of the invention, the excess steam produced in the vapor compression system is used to supply heat to a feed to a multi-stage flash evaporation system. In accordance with other embodiments, the excess steam is passed through a turbine to generate power. The excess steam generated in the system may be passed to other uses directly from the jet compressor or all of the steam withdrawn from the jet compressor may be passed to the vapor compression evaporation system, with a portion of the steam generated in the lower pressure vapor compression effect being passed to the vapor compressor and the remaining portion being passed to other uses. Thus, excess steam may be defined as that quantity of steam which cannot be utilized in the multi-effect vapor compression evaporation system.

The motive fluid for the jet compressor may be at a pressure between about 450 and 1750 p.s.i.g., or as high as 2000 p.s.i.g., preferably between about 1000 and about 1500 p.s.i.g. The jet compression system may comprise one or more jets arranged in parallel or series or a combination of both and the term jet or jet compression system as used herein includes such combinations. The vapor compression evaporation system contains at least one effect, generally two or more effects, with the choice of the exact number of effects and both the particular effect at which the low pressure vapor is withdrawn and the particular effect at which the higher pressure vapor is introduced being within the scope of those skilled in the art. In general, the lower pressure vapor is withdrawn from one of the initial effects and the higher pressure vapor withdrawn from the jet compressor is introduced into the first effect.

The motive fluid may be either water or steam, with water being more economical for effecting compression of vapor over a narrow pressure range. The high temperature water develops steam and due to the high density thereof, attains a lower velocity compared to superheated steam.

The invention will be further described with reference to the accompanying schematic drawings in which valves and the like have been omitted to simplify the description thereof. The choice of particular operating equipment and the placing of suitable valves and the like are considered to be within the scope of those skilled in the art. The invention is particularly described with reference to the evaporation of brine, but it is to be understood that the invention is equally applicable to the evaporation of other liquids, including brackish water, chemical or sewage effluent waste water, and the like. The mnlti-effect evaporation system and particular evaporating effects employed are those known in the art and are operated in a manner known in the art, e.g., feed water thereto is pretreated to remove scale forming chemicals.

Referring now to FIGURE 1, water at an elevated temperature, and pressure, for example about 1000 to about 1500 p.s.i.g., from a feed tank 10 is passed through line 11 and a high pressure heat exchanger 12, wherein the temperature of the water is raised to about 400-600 F. The heat exchanger 12 may be a high pressure boiler wherein the water is heated by indirect heat transfer with a suitable heat transfer agent, for example, with a gas turbine exhaust gas. The heated water from heat exchanger 12 is passed through line 13 and a portion thereof passed through. line 14 to maintain a .vacuum in a flash evaporation system, as hereinafter described. The remaining portion of water in line 13 is passed through line 15 and introduced into a jet compressor 16. The introduction of the high pressure, high temperature water into the jet compressor 16, draws low pressure steam, for example at a pressure of 16 p.s.i.a., in line 17, into the jet compressor 16 wherein the pressure of the steam is raised to a higher pressure, for example, 25 p.s.i.a. The low pressure steam in line 17 is obtained from the last effect of a multi-efiect distillation system as hereinafter described. A steam-water mixture is passed from the jet compressor 16 into a vapor-liquid separator 18 wherein the steam and water are separated. The water is withdrawn from the separator 18 through line 19 and returned to the feed tank 10.

The higher pressure steam is withdrawn from separator 18 through line 21 and a portion thereof pased through line 22 to supply the heat requirements for a multi-eifect distillation system, generally indicated as 23. The remaining portion of the steam is passed through line 24- to meet a portion of the heat requirements of a flash evaporation or distillation system, as hereinafter described.

The distillation system is illustrated as having three efiects, eifects 25, 26 and 27, respectively, but it is to be understood that more or less eifects, for example only one effect, may be employed with the exact number of effects employed to obtain optimum conditions being within the scope of those skilled in the art. A feed for the distillation system 23, such as brine, in line 28 is passed through line 29 and heat exchanger 31 wherein the brine is heated by indirect heat transfer with product water from the distillation system 23. The heated brine from heat exchanger 31 is passed through line 32 and heat exchanger 33 wherein the brine is further heated by indirect heat transfer with the brine eliminated from the distillation system 23. The heated brine from heat exchanger 33 is passed through line 34 and introduced into the first eifect 25 of the distillation system 23. A portion of the brine in the first eifect 25 is vaporized to steam by indirect heat transfer with the steam introduced therein through line 22, concurrently condensing the steam. The steam generated in the first effect 25 is withdrawn therefrom through line 35 and introduced into the second etfect 26. The unvaporized brine in the first effect 25, is withdrawn therefrom through line 36- and introduced into the second eifect 26 wherein a further portion is vaporized to steam by indirect heat transfer with the steam introduced through line 35. The steam is condensed as a result of the indirect heat transfer.

The steam generated in the second effect 26 is withdrawn therefrom through line 37 and introduced into the third eifect 27. The unvaporized brine in the second effect 26 is withdrawn therefrom through line 38 and introduced into the third effect 27 wherein a further portion is vaporized to steam by indirect heat transfer with the steam introduced through line 37. The steam introduced through line 37 is condensed as a result of the heat transfer. The steam generated in the third effect is withdrawn therefrom through line 17 and passed to the jet compressor 16, as hereinabove described.

The steam condensate from etfects 25, 26 and 27 is withdrawn through line 39, 41 and 42, respectively, combined in line 43 as product water and passed through heat exchanger 31, to indirectly heat the feed to the distillation system 23. The product water from heat exchanger 31 is passed through line 44 to storage or use.

The unvaporized brine from the third effect 27 is withdrawn therefrom through line 45, passed through heat exchanger 33 to indirectly heat the feed to the distillation system 23 and passed through line 46 to waste.

A portion of the feed brine in line 28 is passed through line 52 and heat exchanger 53 wherein the temperature of the brine is raised by indirect heat transfer with steam and non-condensible gases being exhausted from a flash distillation system, as hereinafter described. The heated brine from heat exchanger 53 is passed through line 54 and introduced into a flash evaporation system, schematically indicated as '55. The evaporation system 55 is of a type known in the art and the exact number of stages employed therein is deemed to be well within the scope of those skilled in the art.

The brine is passed through the condenser tubes (not shown) of the flash distillation system 55 and further heated therein by indirect heat transfer with the vapor generated in the system. The preheated brine is withdrawn from the flash evaporation system 55 through line 56 and passed through heat exchanger 57 wherein the brine is heated by indirect heat transfer with excess steam from the jet compressor introduced through line 24. As a result of the indirect heat transfer, the steam is condensed and passed through line 58 to the feed tank 10. Make-up water is introduced into the feed tank 10 through line 60.

The heated brine from heat exchanger 57 is passed through line 59 to the flash evaporation system 55 wherein the brine is flashed in successive evaporation stages as known in the art. The product water is withdrawn from the flash evaporation system 55 through line 61.

The vacuum required in the flash evaporation system 55 is produced by a two-stage jet, generally indicated as 62, connected to the system 55 through line 63. The jet 62 is operated by the high temperature high pressure water obtained from the heater 12 through line 14. The noncondensible gases and steam are withdrawn from the jet 63 through line 65 and passed through heat exchanger 53 to indirectly heat the brine feed to the flash evaporation system 55. The steam and non-condensible gases are withdrawn from the heat exchanger 53 through line 66 and the steam may be condensed (not shown) and used as make up water to the system through line 60.

In FIGURE 2, there is illustrated a modification of the embodiment illustrated in FIGURE 1, with like parts being designated by like numerals. The jet compressor 16, the means for generating the water motive fluid for the jet compressor 16, the distillation system, the means for feeding brine to the distillation system, function in a manner similar to the embodiment illustrated in FIGURE 1 except that two effects instead of three effects are employed. This embodiment differs from the embodiment illustrated in FIGURE 1, in that all of the steam from the jet compressor 16 is passed to the distillation system and excess steam is withdrawn from the second eifect and used for operating a turbine.

Referring now to FIGURE 2, steam is withdrawn from the second evaporator eflfect 26 through line 101 and a portion thereof introduced into the jet compressor 16 through line 102. The remaining portion of steam is passed through line 103 to a low pressure condensing turbine 104, driving a power generator 105. The power generated may be used, for example, to produce more water by driving a compressor for a mechanical vapor compression system. The steam is withdrawn from turbine 104 through line 106, condensed in condenser 107 and passed through line 108 to the feed tank 10 The steam is condensed in condenser 107 by brine passed therethrough through line 109. The partially heated brine from condenser 107 is passed through line 111 as feed to the distillation system, through line 29 and heat exchangers 31 and 33 either arranged in series (as shown) or in parallel (not shown).

In FIGURE 3, there is illustrated another modification of the embodiment illustrated in FIGURE 1, with like parts being designated by like numerals. The distillation system and the means for feeding brine to the system function in a manner similar to the embodiment of FIGURE 1. This embodiment dilfers from the embodiment of FIG- URE 1 in that the jet compressor is driven by steam and in that excess steam is used in a two stage high and low pressure turbine.

Referring now to FIGURE 3, water in feed tank 10 is passed through line 201 and a heat exchanger 202, such as a high pressure boiler, wherein the water is converted to high pressure steam. The steam from boiler 202 is passed through line 203 and a portion thereof passed through line 204 to a turbine, as hereinafter described. The remaining portion of steam in line 203 is passed through line 205 and introduced into a jet compressor 206. The steam draws low pressure steam in line 17, obtained from the last evaporation effect 27 of the distillation system 23 into the jet compressor 206 wherein the pressure of the steam is raised to a higher pressure.

The higher pressure steam is withdrawn from jet compressor 206 through line 207 and a portion thereof passed through line 208 to the distillation system 23. The remaining portion of steam in line 207 is passed through line 209 to the low pressure part 211b of a two-stage high pressurelow pressure turbine 211.

The high pressure steam in line 204 obtained from boiler 202 is passed to the high pressure part 211a of the turbine 211. The exhaust steam from the high pressure part 211a is passed through line 212 to the low pressure part 2111; of the turbine 211. The turbine 211 operates a power generator 213.

Exhaust steam from the low pressure part 211b of the turbine 211 is withdrawn through line 214, condensed in condenser 215, supplied with a suitable heat transfer agent through line 216, and passed through line 217 to the feed tank 10.

Numerous modifications of the present invention are possible in the light of the above teachings. Thus, for example, the excess steam produced by the vapor compression system of the embodiment of FIGURE 1, could be used as a steam source for a multi-effect evaporation system instead of as a heat source for a multistage flash evaporation system. More particularly, a portion of the excess steam from the last effect of the distillation system is passed to the first effect of a multi-eifect evaporation system. The above modification and other modifications should be apparent to those skilled in the art from the teachings contained herein.

The evaporation system of the invention which employs a jet compressor or compressors has numerous advantages over evaporation systems heretofore known in the art. The efliciency of the system is very high since all excess steam is utilized either as a power source or as a source of heat for another evaporation system. The equipment is much simpler than mechanical compression systems in that the compressor and drive are eliminated and in that the steam produced is saturated thereby eliminating the need for a de-superheater. In addition, operating costs are reduced by the substitution of stationary jet compression nozzles for highly sensitive rotating machinery which is subject to scaling and costly maintenance.

Numerous modifications of the invention are possible in light of the teachings contained herein. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as particularly described.

What is claimed is:

1. A process for evaporating an impure liquid to effect recovery of a distilled liquid comprising:

(a) introducing a first portion of the impure liquid to be evaporated into a multi-efl'ect evaporation zone;

(b) vaporizing liquid within said multi-eifect evaporation zone to produce vapor of the corresponding liquid;

(c) condensing a portion of said vapor from the multietfect evaporation zone to recover distilled liquid;

(d) introducing another portion of the vapor derived from the impure liquid in the multi-elfect evaporation zone into a jet compression zone;

(e) introducing a high pressure, high temperature liquid as a motive fluid for said jet compression zone, to raise the pressure of said another portion of vapor thereby producing compressed vapor;

(f) passing one portion of said compressed vapor to the multi-effect evaporation zone to provide heat requirements therefor;

(g) introducing a second portion of said liquid to be evaporated into a flash evaporation zone;

(h) evaporating liquid in said flash evaporation zone;

(i) condensing vapor produced in the flash evaporation zone to recover distilled liquid; and

(j) passing a second portion of the compresed vapor produced in step (e) in an indirect heat transfer relaship with liquid in the flash evaporation zone to provide heat requirements therefor.

2. The process as defined in claim 1 wherein the liquid motive fluid is at a pressure between about 450 and 1750 p.s.1.g.

3. The process as defined in claim 2 wherein the impure liquid to be evaporated is an aqueous liquid and the motive fluid is Water.

4. The process as defined in claim 3 wherein the motive fluid is at a temperature between about 400 F. and 600 F.

5. The process as defined in claim 1 wherein the second portion of the compressed vapor is condensed as a result of the heat transfer in step (j) and further comprising compressing the condensate from step (j), heating said compressed condensate and employing said heated and compressedcondensate as the motive fluid in said jet compression zone.

6. The process as claimed in claim 5 and further comprising passing the impure liquid feed to the multi-effect evaporation zone in an indirect heat transfer relationship with the distilled liquid recovered from the multi-effect evaporation zone.

7. The process as defined in claim 6 and further comprising maintaining a vacuum in said flash evaporation zone by passing high tempearture, high pressure water as motive fluid through another jet compression zone maintained in fluid flow communication with the flash evaporation zone.

8. An apparatus for evaporating an impure liquid to effect recovery of a distilled liquid comprising:

(a) a multi-eflect evaporation system;

(b) means for introducing a first portion of the impure liquid to be evaporated into the multi-effect evaporation system;

(c) means for vaporizing liquid within said multi-effect evaporation system to produce vapor of the corresponding liquid;

(d) means for condensing a portion of said vapor from the multi-ei'fect evaporation system to recover distilled liquid;

(e) a liquid operated jet compressor;

(f) means for introducing another portion of the vapor derived from the impure liquid in the multi-effect evaporation system into the jet compressor;

(g) means for introducing a high pressure, high temperature liquid into the jet compressor as a motive fluid therefor to raise the pressure of said another portion of vapor thereby producing compressed vapor;

(h) means for passing one portion of said compressed vapor to the multi-etfect evaporation system to provide heat requirements therefor;

(i) a flash evaporation system;

(j) means for introducing a second portion of said liquid to be evaporated into the flash evaporation system;

(k) means for evaporating liquid in the flash evaporation system;

(1) means for condensing vapor produced in the flash evaporation system to recover distilled liquid; and

(111) means for passing a second portion of the compressed vapor produced in the jet compressor in an indirect heat transfer relationship with liquid in the flash evaporation system to provide heat requirements therefor.

References Cited UNITED STATES PATENTS Worthen et a1 202174 X Worthen et a1 20311 Worthen et a1 202-173 Hickman 20326 X Checkevich 20311 Lynam 20311 X Goldner 20211 X Jebens et a1 202173 8 3,391,062 7/1968 Tidball 20311 3,405,037 10/1968 Aronson et a1 20311 X FOREIGN PATENTS 937,623 9/1963 Great Britain.

US. Cl. X.R. 

